Barkdust Mulch Benefits
Benefits of barkdust and mulch can't be overstated. The benefits include:
1. Reduces irrigation water costs and water loss from soil by up to 80%
2. Reduces ET (evaportranspiration) from the plants by up to 25% (Texas A&M University research)
3. Prevents surface compaction from impact of rain
4. Insulates soil and can increase weeks of root growth during late autumn
I learned how important bark and mulch was around 1980. At my parent's property we planted 30 Rhododendrons in June or July under Douglas Fir trees - a shaded area of bare soil with no mulch. The temp was mid-80 degrees. But the top foliage of these plants drooped within 24 hours, everyday, with daily watering.
Finally, we bought one cubic yard of barkdust and laid a 36 inch circle around each Rhododendron about 1” deep. Within two days the leaves perked up, and no drooping of leaves. In one week there was new growth sprouting. Within a week the soil around the planting holes changed from brick-like to moist and pliable. The barkdust promoted new plant growth and better soil conditions.
Soil benefits from an organic top layer and bark mulch provides that. As it decomposes, compounds like polysaccharides and glomalin release down into the soil improving soil condition and structure.
Barkdust reduces compaction from rain, reduces erosion and holds moisture. It also insulates roots and soil from freezing temperatures. Much of a shrub or tree's root growth happens mid-autumn into December. Bark mulch will buffer soil soil temperature and add several weeks of extra root growth.
Bark is useful for tree root preservation at construction sites. If thick layers are placed around the drip line of trees, soil compaction can be prevented.
The use or absence of barkdust or mulch frequently makes or breaks the success of newly planted trees and shrubs in landscaping.
Calculating coverage
We do not supply, but referrals you can call in norther Oregon include: S & H Logging near Stafford Rd. x 205 and Grimm's Fuel in Tigard. In southern Oregon, try Hilton Landscape Supply, Biomass One and Ground Control. If you don't know how to measure your yard and calculate for an order, a few tips are offered below.
Most likely, you will order by cubic yard or by truck load. In Oregon, truck loads are typically "one unit" (7.5 cubic yards). This page is written assuming 1 truck load is a "unit".
One unit covers 1100 square feet 2 inches deep. It will cover eleven 10' x 10' areas 2 inches deep, because each 10' x 10' area equals 100 square feet. If you only spread the load 1 inch deep, the 7.5 cu. yd. unit will cover 2200 square feet or twenty-two 10' x 10' areas.
A single cubic yard covers roughly 150 square feet 2 inches deep like 15' x 10' or a narrow strip like 5' x 30''. So you just need to measure your soil areas or shrub beds to find out the total number of square feet.
I divide all the areas into basic shapes. Rectangles, circles and triangles. If shrubs beds in a landscape are irregular I still try to divide them into a crude combination of rectangles, circles and triangles and add together.
For example, look to the right at the shape resembling a crude house drawing. That is divided into a rectangle plus a triangle. That one would be 18 square feet for the rectangle part and 12 square feet for the triange part, or 30 square feet altogether.
Rectangles: multiply length by width. Like the one to the right: 3 x 10 = 30 square feet. If that was 30 x 20 then it would be 600 square feet of area.
Triangles: multiply length X width and divide in half. The triangle to the right has sides of 4 x 4 = 16. Then divide that 16 by 2: the triangle has a total surface area to cover of 8 square feet.
Circles: Area of a circle is derived from Area = Π x r2
Π (Pi) = 3.14. And the area equals 3.14 x radius squared. Radius is half the diameter.
The circle to the right has a diameter of 10, so the radius is 5. The area is 3.14 x 52. Or, written 3.14 x 25 = 78.5. That is the area of that circle in square feet. It needs enough mulch to cover 78 square feet if we round the number. You could actually round 78.5 up to an even 80 square feet.
Irregular Areas: You can see what I did to the right with one irregular shape. Guess-timated and overlaid an approximate rectangle to simplify measurement rather than chopping all the lobes into little separate pieces.
Circle Chart
Since circles may be a bit awkward for some folks to do the math, here is a circle solver chart to the right for several circle sizes. The chart is based on the circle diameter (width) rather than radius.
Circle Solver Calculator
If you want to calculate online for the square feet of other size circles, search for circle area solver or circle area calculator and you should find a few free ones to use. Just enter numbers in the boxes and click enter. The math will be done automatically.